In a conventional transport system of the above type, the driven wheel of the electric conveying rail cars is customarily rotated by a modified electric motor for driving the rail .car, having a built-in electromechanical brake. In these prior art devices the electric conveying rail car has a high production cost and a complicated way of releasing and applying the built-in electromechanical brake of the electric motor when it is desired to move the electric rail car manually or by an external supplementary conveyor in a special rail section. That is, the stopping and starting of the electric rail car involves a considerable input of labor.